Hematologists' state of knowledge on practical aspects of hemophagocytic lymphohistiocytosis (HLH) in adult patients: A Young Hematologists' Club survey.

Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome with various etiologies. Its treatment is complicated by several important but not immediately obvious issues (e.g., HLH-2004 criteria are the most commonly used for diagnosis, but the recommended therapeutic regimen is HLH-94).

Objectives: The study aimed to assess hematologists' practical knowledge of HLH.

Material and methods: A survey was conducted among physicians treating adult hematological patients. A 10-question paper questionnaire was distributed to physicians from various hematology centers. A total of 126 questionnaires were analyzed.

Results: Most respondents had little-to-moderate experience in caring for HLH patients: 59% treated 0-2 patients and 36% treated between 3-5 patients. Among the respondents, the preferred diagnostic criteria were HLH-2004, either in its original form (5 out of 8 criteria) for 70 respondents or its modified version (4 out of 6 available criteria when ferritin exceeds 2,000 ng/mL) for 56 respondents. The preferred treatment regimen was HLH-2004, with a full dose of etoposide in 72 responses or reduced in 39 responses. Fifty percent of respondents incorrectly answered that meeting the HLH-2004 criteria necessitates the use of the HLH-94/2004 regimen in full doses and duration. Sixty-four percent of respondents correctly identified that hemophagocytosis is not necessary for the diagnosis.

Conclusions: This survey reveals that the majority of surveyed physicians adhere to international HLH recommendations. However, there are instances where these guidelines are not fully implemented, which underlines the need for further efforts to raise awareness and share clinical experiences about this patient group.